The present technique relates generally to the measurement of mechanical organ motion internal to a subject. More specifically, the present technique relates to measuring internal organ movement via an array of external sensors, such as accelerometers, disposed along the body surface of a subject.
In the medical fields, it is often desirable to measure and characterize the motion of internal organs, such as the heart or lungs, for diagnosis, for processing or interpreting medical imaging data, or for other purposes. In particular, such motion may be indicative of cardiac or respiratory abnormalities that may not be evident from other techniques. Such motion, however, is obviously not directly observable absent an invasive procedure, i.e., surgery, which may be otherwise unnecessary.
As a result, various indicators which can be measured non-invasively may be used as surrogates for the motion of the underlying organ. For example, electrocardiography may be used to measure depolarization of the cardiac muscle tissue, which can then be used to estimate the timing of the contraction phases of the cardiac cycle. In particular, during each phase, different cardiac cells are depolarizing and, presumably, undergoing the subsequent mechanical event of contraction. However, motion aberrations or abnormalities in which the mechanical event of contraction is disassociated from the electrical event of depolarization, due to tissue defect, ionic imbalance, or whatever, may lead to motion defects or abnormalities that are undetected based upon the electrical event depolarization. In such instances, the actual motion of the heart may not be predictable or discernible based on an electrocardiogram, leaving the abnormality undetected and uncorrected.
One alternative is to attempt to measure the underlying motion of the organ of interest using sufficiently sensitive motion sensors, such as, accelerometers, in contact with the surface of the patient. However, because the motion of the organ underlying the surface occurs in three spatial dimensions, a single point measurement from such a sensor is insufficient to accurately represent the full motion of the organ. In particular, a single measurement provides insufficient information to resolve all three spatial dimensions of the internal organ at a moment in time. Therefore, a need exists for a technique allowing the accurate determination of the actual motion of an internal organ in a non-invasive manner.